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Section 4 Caches
4.1
Overview
4.1.1
Features
An SH7750 or SH7750S has an on-chip 8-kbyte instruction cache (IC) for instructions and 16-
kbyte operand cache (OC) for data. Half of the memory of the operand cache (8 kbytes) may
alternatively be used as on-chip RAM. The features of this cache are summarized in table 4.1
The SH7750R has an on-chip 16-kbyte instruction cache (IC) for instructions and 32-kbyte
operand cache (OC) for data. Half of the memory of the operand cache (16 kbytes) may
alternatively be used as on-chip RAM. When the EMODE bit of the CCR register is 0, the
SH7750R’s cache is set to operate in the SH7750/SH7750S-compatible mode and behaves as
shown in table 4.1. The features of the cache when the EMODE bit in the CCR register is 1 are
given in table 4.2. The EMODE bit is initialized to 0 after a power-on reset or manual reset.
For high-speed writing to external memories, the SH7750 series supports 32 bytes
×
2 of store
queues (SQ). Table 4.3 lists the features of these SQs.
Table 4.1
Cache Features (SH7750, SH7750S)
Item
Instruction Cache
Operand Cache
Capacity
8-kbyte cache
16-kbyte cache or 8-kbyte cache +
8-kbyte RAM
Type
Direct mapping
Direct mapping
Line size
32 bytes
32 bytes
Entries
256
512
Write method
Copy-back/write-through selectable
Table 4.2
Cache Features (SH7750R)
Item
Instruction Cache
Operand Cache
Capacity
16-kbyte cache
32-kbyte cache or 16-kbyte cache +
16-kbyte RAM
Type
2-way set-associative
2-way set-associative
Line size
32 bytes
32 bytes
Entries
256 entries/way
512 entries/way
Write method
Copy-back/write-through selectable
Replacement method
LRU (least-recently-used) algorithm LRU algorithm
Содержание SH7750 series
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